The present invention relates generally to fuel cell assemblies and, more particularly, to the oxidation and fuel distribution to fuel cells, such as solid oxide fuel cells.
A fuel cell is an energy conversion device that produces electricity by electrochemically combining a fuel and an oxidant across an ionic conducting layer. One typical construction of a high temperature fuel cell bundle is an array of axially elongated tubular shaped connected fuel cells and associated fuel and air distribution equipment. Other fuel cell constructions include planar fuel cells comprising flat single members. Exemplary planar fuel cells include counter-flow, cross-flow and parallel flow varieties. The members of a typical planar fuel cell comprise tri-layer anode/electrolyte/cathode components that conduct current from cell to cell and provide channels for gas flow into a cubic structure or stack.
Fuel cell stacks, such as solid oxide fuel cell stacks, have demonstrated a potential for high efficiency and low pollution in power generation. In a solid oxide fuel cell, upon electrochemically combining a fuel and an oxidant across an ionic conducting layer, an oxygen ion (02−) transported across the electrolyte produces a flow of electrons to an external load.
Oxidant, generally air, performs two main functions in the fuel cell stack. As discussed above, the oxidant electrochemically reacts with fuel to generate electric power. In addition, the oxidant is utilized to remove excess heat away from the cell. The waste heat generated in a solid oxide fuel cell at its operating temperature of about 600° C. to about 1300° C. is typically removed via the oxidant to maintain a desired temperature level of the fuel cell components, such as the anode, cathode and electrolyte.
For the stack to operate at maximum efficiency, all of the cells in the stack should operating at substantially the same operating temperature and have substantially the same reaction rate. In order to achieve this maximum efficiency, each cell requires about an equal amount of oxidant and fuel to be delivered.
Accordingly there is a need in the art to have an improved oxidant and fuel distribution system that can consistently deliver oxidant and fuel to the entire cell.